JPH0753958B2 - High compression strength corrugated board production method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a high compression strength corrugated fiberboard base paper, and particularly to a compression strength required for a base paper processed and molded into a corrugated board or a paper box, for example, a ring crush strength. It provides an increased method of making paper.

[Prior Art] Paper strength enhancers in the paper manufacturing industry include various high molecular weight substances such as starch and modified starch, and cellulose derivatives, acrylamide polymers, polyvinyl alcohol, polyamide, polyethyleneimine, and urea resins. , Various synthetic polymer substances such as melamine resin and polyamide polyamine epichlorohydrin resin have been used alone or in combination of two or more thereof. Among these paper-strengthening agents, cationic ones have a so-called self-fixing ability that is effectively adsorbed on the fiber surface because the cellulose fiber surface is weakly anionic. On the other hand, anionic or nonionic paper strengthening agents do not have self-fixing ability, so they are adsorbed on the fiber surface by using a fixing aid, or are directly applied to the paper by mechanical operation. Therefore, the effect is expressed.

In recent years, amphoteric polymer substances that use both a cationic group and an anionic group have come to be used as a paper-strengthening agent having self-fixing ability.

[Problems to be Solved by the Invention] In recent years, in the field of secondary processing of paper, for example, in the industrial fields such as corrugated board, box making, gypsum board, and printing, demands for paper performance have become higher and higher. Various chemicals are used upon request. Of these, reinforced corrugated cardboard is often processed into a packaging box, and in this case, it is piled up at the time of protection, storage, or transportation of the contents, which is its own function, so it is better than general burst strength or tensile strength. Also, it is required to increase the compressive strength, for example, the ring crush strength. However, since the compressive strength of paper and the general strength of paper are not necessarily proportional to each other, it has been difficult to produce a paper having a sufficiently excellent compressive strength by a conventional paper making method.

However, as an attempt to increase the compressive strength, a papermaking method in which a cationic polymer compound and an anionic polymer compound are used in combination is known, which makes it possible to obtain a paper having a considerably high compressive strength. . However, the paper obtained by this method has too high a wet strength, and has a drawback that it is difficult to disintegrate and recover broke that is unavoidable in the paper manufacturing process,
In addition, since it is necessary to add a paper strengthening agent in a high amount, it cannot be said to be advantageous in terms of economy.

As a result of earnest research to enhance the compressive strength of paper, the present inventors have found that when a cationic polymer compound and PAC are used in combination,
It was discovered that a paper having an excellent compressive strength can be obtained without particular difficulty in disaggregating broke, and a new method for producing high compressive strength paper was proposed (see Japanese Patent Laid-Open No. 55-122099).

However, in the above method, the water drainage on the paper machine wire may be deteriorated due to the difference in the type of paper machine and other papermaking conditions, or the wire or blanket or roll may be soiled. There was an inconvenience in the practical implementation.

The present invention solves the above problems in the prior art and provides an economical and industrially suitable method for producing a high compressive strength paper.

[Means for Solving Problems] According to the present invention, an amphoteric polymer compound and a basic polyaluminum hydroxide compound are added to a pulp slurry, which is a raw material for papermaking, without adding a filler, and then papermaking is performed according to a conventional method. It has been clarified that it is possible to achieve the above-mentioned object of the present invention by a method for producing a high compression strength paper characterized by the above. The structure of the present invention will be described in detail below.

In the paper manufacturing process to which the present invention is applied, all known types of pulp, for example, ground pulp, mechanical pulp such as TMP, chemical pulp such as sulfite pulp and kraft pulp, recycled waste paper pulp from recovered waste paper such as corrugated board or newspaper, etc. Etc. can be used, and a mixture of one or more kinds of various natural or synthetic organic or inorganic fiber substances can be used. However, in any case, no filler is added to the pulp slurry for paper making in the present invention.

The amphoteric polymer compound used in the present invention is a water-soluble or water-dispersible polymer compound having both a cationic group and an anionic group in its molecular structure. Can be exemplified by various amine groups based on primary amine, secondary amine or tertiary amine structure, quaternary ammonium base and the like, and as anionic groups, carboxyl group, sulfonic acid group, Examples thereof include phosphoric acid groups or groups such as metal salts and amine salts thereof.

The content of the cationic group and the anionic group in the amphoteric polymer compound is 1 g (solid content) of the amphoteric polymer compound,
Cationic group 0.5 meq or more, anionic group 0.15-4
It is desirable that the amount is milliequivalent and the equivalent ratio of the cationic group and the anionic group is 0.5 or more. Particularly, as the amphoteric polymer compound, acrylamide, methacrylamide, or both of them [hereinafter referred to as "(meth) acrylamide", and may be indicated with the same meaning. It is most effective to achieve the object of the present invention to select an amphoteric acrylamide-based polymer which contains [] as a main constituent component and has a cationic group and an anionic group introduced by any known means.

As a specific method for producing an amphoteric acrylamide-based polymer, a monomer mixture containing (meth) acrylamide and at least three kinds of monomers of a cationic group-containing monomer and an anionic group-containing monomer may be prepared by various known polymerization means. A method of copolymerizing by using a cationic group by modifying a nonionic acrylamide polymer such as poly- (meth) acrylamide or a copolymer of (meth) acrylamide and a nonionic copolymerizable monomer. Method for obtaining amphoteric acrylamide polymer by introducing anionic group, cationic acrylamide polymer or anion which is a copolymer of (meth) acrylamide and cationic group-containing monomer or anionic group-containing monomer By modifying the ionic acrylamide polymer, anionic groups or cationic groups are prepared. It is possible to employ a method or the like to obtain an amphoteric acrylamide polymer by introducing the down groups.

In the above amphoteric acrylamide polymer, the content of the cationic group is 3 to 60 mol% based on the constituent monomer units of the polymer, and the content of the anionic group is 1 to 25.
Must be mol%. When the content of each ionic group is outside the above range, it is difficult to achieve the object of the present invention in any case. Particularly preferred ranges are 6 to 50 mol% of cationic group content and 3 of anionic group content.
Is in the range of up to 20 mol%.

The content ratio of the cationic group and the anionic group in the amphoteric acrylamide polymer is appropriately 1/1 to 20/1,
Under normal papermaking conditions, good results are obtained in the range of 1.5 / 1 to 5/1.

Specific examples of the most preferable amphoteric acrylamide polymer are (i) (a) (methacrylamide 50 to 96 mol% (b) alkylaminoalkyl (meth) acrylamide 3 to 20 mol% (c) (meth) acrylic acid 1 to Amphoteric acrylamide polymer, which is a multi-component copolymer containing 10 mol%, (ii) 3 to 20 mol% of poly- (meth) acrylamide
Reaction of formaldehyde and secondary amine with an anionic acrylamide polymer containing 3 to 20 mol% of anionic groups obtained by copolymerizing 3 to 20 mol% of a hydrolyzate or (meth) acrylic acid. A Mannich reaction product of an anionic acrylamide-based polymer containing 6 to 50 mol% of a dialkylaminomethyl group obtained at most.

The above-mentioned (i) amphoteric acrylamide-based polymer is not necessarily advantageous in terms of economical efficiency because (b) alkylaminoalkyl (meth) acrylamide is very expensive, but in other respects, the object of the present invention is achieved. Is extremely effective for

The amphoteric acrylamide-based polymer of (ii) above is a poly-
It is most suitable for the purpose of the present invention in that it can be easily obtained by modification of (meth) acrylamide, and that economical and high compression strength paper can be obtained.

The basic polyaluminum hydroxide compound used in the present invention has a main component of [Al ₂ (OH) _n Cl _6-n ] _m or [Al
(OH) ₃ ] _n AlCl ₃ is a high molecular weight water-soluble aluminum salt, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al
It contains basic polynuclear condensed ions with a high positive charge such as ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ^5+, etc. JISk- for water treatment. Its properties are specified in 1475. These are commercially available as polyaluminum chloride (PAC) or polyaluminum hydroxide (Paho) from Taki Chemical Co., Ltd. and Asada Chemical Co., Ltd., and any of them can be preferably used.

The amount of the amphoteric polymer compound and the basic polyaluminum hydroxide compound used in the practice of the present invention is not particularly limited, but its effect, that is, the value of the compression strength of the target paper and the economical efficiency, etc. In consideration of the above, it can be arbitrarily changed as appropriate. Generally, the amphoteric polymer compound is in the range of 0.05 to 3% and the basic polyaluminum hydroxide compound (as Al ₂ O ₃ content) is in the range of 0.05 to 1% with respect to the dry pulp weight.

The practice of the present invention does not require any special procedure or equipment, and may be applied as it is to a normal papermaking process. For example, a mixing pulp, a machine chest or a raw material pulp slurry such as a seed box is used as an amphoteric polymer compound and a basic compound. Highly compressive strength paper can be easily produced by adding a polyaluminum hydroxide compound at the same time or sequentially and then performing papermaking according to a conventional method.

[Function] Conventionally, a basic poly (aluminum hydroxide) compound has been known as a fixing aid for an anionic group or a nonionic additive, and is a cationic or amphoteric additive having a self-fixing ability. It was an unnecessary auxiliary agent.

However, the present inventors have discovered the additive effect of both of them on improving the compressive strength of paperboard.

Cationic polymer and polyaluminum chloride (PA
In the earlier application relating to the combined use with C), the surface charge of the dispersed particles of the papermaking raw material system was excessively biased to the positive side, and
Insufficient binding between the polymer compound and PAC hinders drainage of water on the paper machine wire and retention of fine fibers, which causes a problem in the operability of the papermaking process with less use of anionic additives. It is thought to have caused it.

In the present invention, by using an amphoteric polymer compound having self-fixing ability, the mutual reactivity between the polymer compound and the basic polynuclear condensed ion of the basic polyaluminum hydroxide compound in the papermaking raw material system is improved. As a result of being increased, a complex having a strong positive charge is formed in the pulp pulp slurry for papermaking, and very finely aggregates fine fibers and other fine particles to generate an appropriate floc without destroying the texture of the paper. It is believed that this is due to the formation of tight webs. Therefore, the papermaking method of the present invention can conspicuously accelerate the drainage of water on the wire of a papermaking machine, and significantly improve the papermaking operability.

[Examples] Hereinafter, the present invention will be specifically described with reference to Preparation Examples, Examples, and Comparative Examples.

Preparation Example 1 A predetermined amount of acrylamide and acrylic acid was dissolved in ion-exchanged water to prepare a 10% mixed monomer aqueous solution, and then an ammonium persulfate aqueous solution and a sodium bisulfite aqueous solution were added to initiate polymerization. After the polymerization heat is stopped, 75 ~ 80 ℃
The mixture was held for 1 hour to obtain an about 10% aqueous solution of anionic acrylamide polymer.

A part of the anionic acrylamide polymer was taken, ion-exchanged water and a dilute caustic potash solution were added and uniformly mixed, and the pH was adjusted to 7.0. Then add a predetermined amount of formalin (37% aqueous solution) and dimethylamine 50% aqueous solution,
The temperature was maintained at 50 to 55 ° C for 1.5 hours to carry out the Mannich reaction of the anionic acrylamide polymer. The properties of the resulting aqueous solution of the amphoteric acrylamide polymer are shown in Table 1.

Example 1 A 2.0% pulp slurry of beaten corrugated waste paper pulp (CSF410 ml) was mixed with a basic polyaluminum hydroxide compound (polyaluminum chloride PAC-250A; manufactured by Taki Chemical Co., Ltd.) Al ₂ O.
_{After 3} minutes, 0.3 was added to the dry weight of the pulp and the mixture was uniformly mixed. Then, 0.3% of an aqueous solution of the amphoteric acrylamide polymer I obtained in Preparation Example 1 (Preparation No. 1-1) (solid content: dry weight of pulp) ) Was added and mixed well. Then, paper was made by a TAPPI standard sheet machine in a usual manner, squeezed and dehydrated at a pressure of 3.5 kg / cm ² for 5 minutes, and then dried by a steam dryer at 105 ° C. for 3 minutes.

The obtained paper had a basis weight of 150 g / cm ^2, and the paper quality was tested after humidity control. The results are shown in Table 2.

Examples 2 to 8 Instead of using the amphoteric acrylamide polymer I in Example 1, the amphoteric acrylamide polymers II to VIII obtained in Preparation Example 1 (Preparation Nos. 1-2 to 1 to 8) were used. Used, otherwise following the same procedure as in Example 1
Various kinds of synthetic paper corresponding to 150 g / cm ² were obtained. Table 2 shows the test results of these paper qualities.

Comparative Example 1 The addition of the amphoteric acrylamide polymer in Example 1 was omitted, and the other procedures were the same as in Example 1 to obtain a comparative paper. The results of the paper quality test are also shown in Table 2.

Comparative Example 2 Addition amount of basic polyaluminum hydroxide compound was 0.6%
Comparative synthetic paper was obtained in the same manner as in Comparative Example 1 except that
The results of the paper quality test are also shown in Table 2.

Comparative Examples 3 to 10 The addition of the basic polyaluminum hydroxide compound in Example 1 and Examples 2 to 8 was omitted, and the other procedures were the same as those in each Example to obtain 8 types of comparative synthetic papers. The results of the paper quality test are also shown in Table 2.

Comparative Example 11 Instead of using the basic polyaluminum hydroxide compound in Example 1, a sulfuric acid band (reagent primary Al ₂ (SO ₄ ) ₃
13-14 H ₂ O) was used, and otherwise the same procedure as in Example 1 was carried out to obtain a comparative synthetic paper. The second paper quality test results
Listed in the table.

Comparative Example 12 The same as Example 1 except that the cationic acrylamide polymer IX of Preparation Example 1 (Preparation No. 1-9) was used in place of the amphoteric acrylamide polymer I used in Example 1. Comparative paper was obtained according to the procedure. The results of the paper quality test are also shown in Table 2.

Test Example 1 Test of drainage (water drainage promoting action) In each of the above Examples and Comparative Examples, each prepared pulp slurry containing 3 g of dry pulp was separated from the prepared pulp slurry before papermaking to which a chemical was added. It was taken, diluted with tap water to 1 and the freeness (CSF) was measured in the usual way. The results are also shown in Table 2.

Examples 9 to 16 and Comparative Examples 13 to 15 Basic polyaluminum hydroxide compounds in Examples 1 to 8 and Comparative Examples 1, 2 and 12 (polyaluminum chloride PAC
-250A), a basic polyaluminum hydroxide compound (polyaluminum hydroxide Paho # 2S: manufactured by Asada Chemical Industry Co., Ltd.) was used, and all other processes were carried out according to the present invention according to the same procedure as in each example. 8 types of high compression strength papers and 3 comparison papers
Got seeds. Table 3 shows the results of paper quality tests conducted on each of the papers. In addition, each of the prepared pulp slurries was sampled, and the freeness (CS
F) is also shown in Table 3.

Preparation Example 2 A 10% aqueous solution of a mixed monomer consisting of 90 mol% acrylamide, 7 mol% dimethylaminopropylacrylamide and 3 mol% acrylic acid was prepared, and diluted sulfuric acid was added to adjust the pH to 4.
Adjusted to 0. Then, an ammonium persulfate aqueous solution and a sodium bisulfite aqueous solution are added to start polymerization, and the temperature is 75 to 80 ° C.
The mixture was kept for 1 hour to obtain an aqueous solution of the amphoteric acrylamide polymer X.

The resulting amphoteric acrylamide polymer aqueous solution has a viscosity
11,000 CPS / 25 ℃, solid content 8%, average molecular weight of polymer 80
It has a cationic / anionic (molar ratio) of 7/3.

Preparation Example 3 Dilute sulfuric acid was added to a 10% aqueous solution of a mixed monomer consisting of 93 mol% acrylamide and 7 mol% dimethylaminopropylacrylamide to adjust the pH to 4.0. Then, an ammonium persulfate aqueous solution and a sodium bisulfite aqueous solution were added to initiate polymerization, and the mixture was kept at 75 to 80 ° C. for 1 hour to obtain an aqueous solution of a cationic acrylamide polymer XI for comparison. The aqueous solution has a viscosity of 9,800 cps / 25 ° C., a solid content of 7% and an average molecular weight of polymer of 900,000.

Examples 17 and 18 Amphoteric acrylamide obtained in Preparation Example 2 was obtained by adding 0.3% of polyaluminum chloride PAC-250A in a dry weight of pulp to a 2% pulp slurry of beaten corrugated waste paper pulp (CSF430 ml) and thoroughly mixing it. A predetermined amount of the aqueous solution of the system polymer X was added and uniformly mixed. The prepared pulp slurry thus obtained was used for papermaking and drying in the same manner as in Example 1 to obtain a high compression strength paper of the present invention. The result of the paper quality test is No. 4
Shown in the table.

Comparative Examples 16 and 17 Instead of using the amphoteric acrylamide polymer in Examples 17 and 18, an aqueous solution of the cationic acrylamide polymer XI obtained in Preparation Example 3 was used to obtain a conditioned pulp slurry. . Hereinafter, a comparative synthetic paper was obtained in the same manner as in Example 17. The results of the paper quality test are also shown in Table 4.

Comparative Examples 18 to 21 The addition of polyaluminum chloride in Examples 17 and 18 and Comparative Examples 16 and 17 was omitted, and the other operations were performed in the same manner as in Examples to obtain a paper for comparison. The result of the paper quality test is No. 4
Also listed in the table.

Test Example 2 A part of the prepared pulp slurry in each of Examples 17 and 18 and Comparative Examples 16 to 21 was sampled, and the freeness of each pulp slurry was measured according to the procedure of Test Example 1. The results are also shown in Table 4.

Examples 19 to 23 A predetermined amount of polyaluminum chloride PAC-250A and amphoteric acrylamide polymer I was added to a 2% pulp slurry of beaten corrugated cardboard waste paper pulp (CSF390 ml), and shaken and stirred to prepare a prepared pulp slurry. , TAPPI standard sheet machine was used to make paper as usual. The wet paper obtained is press dehydrated at a pressure of 3.5 kg / cm ² for 5 minutes, and then at 105 ° C.
Was dried for 3 minutes with a steam dryer to obtain a high compression strength paper according to the present invention. Table 5 shows the results of the paper quality test conducted after humidity control. Further, a part of the prepared pulp slurry before papermaking was sampled and the freeness was measured according to Test Example 1. The results are also shown in Table 5.

Comparative Examples 22-26 The same 2% pulp slurry used in Examples 19-21 was added to a commercially available anionic acrylamide paper strength enhancer (concentration
15% product, anionic group content about 10 mol%, viscosity 15000cps
(/ 25 ° C) and add sufficient amount to shake and stir,
Sulfuric acid band (as Al ₂ O ₃ min) 0.25% was added and mixed thoroughly again with stirring. Next, a commercially available cationic strength agent (concentration 7% product, cationic group content about 20 mol%, viscosity 30
A predetermined amount (0 cps / 25 ° C.) was added, the mixture was shaken and stirred, and then paper-making and drying were carried out in the same manner as described above to obtain a paper for comparison. The results of the paper quality test are shown in Table 5. Further, a part of the prepared pulp slurry before papermaking is sampled and the freeness is measured according to the procedure of Test Example 1. The results are also shown in Table 5.

[Effects of the Invention] The method for producing high compression strength paper of the present invention can be applied to an existing papermaking process very easily, and is particularly effective in improving the compression strength required for corrugated fiberboard. .
Further, as compared with the conventional method of using a paper-making method in which an anionic paper strength enhancer and a cationic paper strength enhancer are used in combination, a high compression strength paper can be obtained in a low chemical addition range, so that the chemical cost can be reduced. Is advantageous in that it is possible to easily disintegrate damaged paper. Furthermore, the papermaking method of the present invention can exhibit a water drainage promoting action at the time of good papermaking under a wide range of papermaking conditions, so that the operability of the papermaking machine is significantly improved and the productivity of the papermaking process is improved. It is possible to improve and save energy consumption.

Claims (4)

[Claims] 1. A method for producing a high-compression-strength cardboard base paper, which comprises adding an amphoteric allylamide polymer and basic polyaluminum hydroxide to a pulp slurry without adding a filler, and then making a paper. 2. The method for producing a high compression strength corrugated fiberboard base paper according to claim 1, wherein the amphoteric acrylamide polymer is a Mannich reaction product of an anionic allylamide polymer. 3. The amphoteric acrylamide-based polymer according to claim 1, which contains (a) a cationic group of 3 to 60 mol% and (b) an anionic group of 1 to 25 mol%. High compression strength cardboard base paper manufacturing method. 4. The method according to claim 1, wherein the molar ratio of (a) the cationic group and (b) the anionic group is (a) / (b) = 1/1 to 20/1. High compression strength cardboard base paper manufacturing method.